00:04
Let's see, we are going to, if you look at number seven, the income of trainees at a local factory are normally distributed with a mean of $1 ,100 and a standard deviation of $150.
00:20
What percentage of a group of eight trainees can have a mean earning of more than $1 ,000 a month? so with n equal to eight, we need to find our standard error by taking 150 divided by the and that is 53 .03.
00:43
So we'll do one minus the probability that z is less than 1 ,000 minus 1 ,100 divided by 53 .03.
00:54
That's going to give us one minus the probability that z is less than negative 1 .89, which corresponds to 0 .0294.
01:03
If we change to a sample of 10, we're going to find the probability that x is less than 1 ,150.
01:12
And again, we have to calculate our standard error by taking 150 divided by the square root of 10.
01:19
And in this case, that's 47 .43.
01:22
So the probability that z is less than 1 ,150 minus 1 ,100 divided by 47 .43.
01:32
So the probability that z is less than 1 .05 corresponds to 0 .8531...